wcn36xx: Remove useless skb spinlock

Each DXE control block is associated to a specific channel.
The channel lock is always taken before accessing a control block.
There is no need to have an extra (useless) spinlock for the control
block skb.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/wcn36xx/dxe.c

@@ -78,7 +78,6 @@ static int wcn36xx_dxe_allocate_ctl_block(struct wcn36xx_dxe_ch *ch)
 		if (!cur_ctl)
 			goto out_fail;
 
-		spin_lock_init(&cur_ctl->skb_lock);
 		cur_ctl->ctl_blk_order = i;
 		if (i == 0) {
 			ch->head_blk_ctl = cur_ctl;
@@ -377,12 +376,11 @@ static void reap_tx_dxes(struct wcn36xx *wcn, struct wcn36xx_dxe_ch *ch)
 				/* Keep frame until TX status comes */
 				ieee80211_free_txskb(wcn->hw, ctl->skb);
 			}
-			spin_lock(&ctl->skb_lock);
+
 			if (wcn->queues_stopped) {
 				wcn->queues_stopped = false;
 				ieee80211_wake_queues(wcn->hw);
 			}
-			spin_unlock(&ctl->skb_lock);
 
 			ctl->skb = NULL;
 		}
@@ -654,8 +652,6 @@ int wcn36xx_dxe_tx_frame(struct wcn36xx *wcn,
 	spin_lock_irqsave(&ch->lock, flags);
 	ctl = ch->head_blk_ctl;
 
-	spin_lock(&ctl->next->skb_lock);
-
 	/*
 	 * If skb is not null that means that we reached the tail of the ring
 	 * hence ring is full. Stop queues to let mac80211 back off until ring
@@ -664,11 +660,9 @@ int wcn36xx_dxe_tx_frame(struct wcn36xx *wcn,
 	if (NULL != ctl->next->skb) {
 		ieee80211_stop_queues(wcn->hw);
 		wcn->queues_stopped = true;
-		spin_unlock(&ctl->next->skb_lock);
 		spin_unlock_irqrestore(&ch->lock, flags);
 		return -EBUSY;
 	}
-	spin_unlock(&ctl->next->skb_lock);
 
 	ctl->skb = NULL;
 	desc = ctl->desc;

drivers/net/wireless/ath/wcn36xx/dxe.h

@@ -422,7 +422,6 @@ struct wcn36xx_dxe_ctl {
 	unsigned int		desc_phy_addr;
 	int			ctl_blk_order;
 	struct sk_buff		*skb;
-	spinlock_t              skb_lock;
 	void			*bd_cpu_addr;
 	dma_addr_t		bd_phy_addr;
 };